Looks like something I'de rig up, don't forget with the limited water volume doing 25% water changes or so daily imo is best particularly if the filter you rigged up isn't already cycled. clean water will only help. glad he seems to be doing better, I would wait to try and feed him until he's doing "ok" and offer him food favorites. with the aeration i would be wary of haveing bubbles going directly against him, a strong current is great but i would avoid actual airbubbles in his "enclosure"
imho lesson learned why the skickys says bass, and cichlids ect make bad tank-mates for gar. spooks happen.. but increase with active fish, and you don't get much more active then cichla and cichlids. food for thought.
I have floating plants in my gar tanks, and driftwood. helps imo alot to keep them in touch with the surface ect.. but spooking happens.. even padding the top ect isn't going to prevent injuries. the surface plants,and driftwood may also grant them a measure of "protection" and prevent spooks in this manner.. but its all only speculation. gars just jump... a well tended tank, with a "secure" feeling will only decrease jumps, ie safe decor/boundries, calm tank-mates, regular lighting ( i've found with my tanks on timers with more "jumpy fish" overall are more calm) water quality maintained lends itself to fewer "accidents" over-all.
3/4 of the fish I own are "spooky" or "jumpers" and i've found a secure feeling fish, no matter how i have to acheive it is a fish thats not going to jump. I've lost my fair share along the way learning this.